A stationary 0.2-g fly encounters the windshield of a 1200-kg automobile traveling at 110 km/h. (a) What is the magnitude of change in momentum of the car due to the fly? (b) What is the magnitude of change of momentum of the fly due to the car? (c) Approximately how many flies does it take to reduce the car's speed by 1 km/h?
2007-07-08 14:42:25 · 2 answers · asked by Sandesh R 1 in Science & Mathematics ➔ Physics
momentum conservation
before =after
1200*[110km/h]+o =(1200+0.0002)V (move together with V)
V = 109.999 km/h
change in momentum of auto = 1200(109.999-110) = 0.0018 kg*km/h = 0.00051 kg*m/s
change in momentum of fly= 0.0002(109.999*5/18) = 0.0061 kg*m/s
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let n flies would be needed (auto speed 110 to 109 km/h)
1200*[110km/h]+o =(1200+ n * 0.0002)109
n * 0.0002 = 11.009
n = 55045.8
or n = 55046 as 55045 would not be able to do
2007-07-08 15:03:29 · answer #1 · answered by anil bakshi 7 · 0⤊ 0⤋
The answer to a, b and c is that the flies missed the car...case closed. =<)
2007-07-08 21:54:48 · answer #2 · answered by Sir Grandmaster Adler von Chase 7 · 0⤊ 0⤋